1. Field of the Invention
The present invention relates to a system for providing a vehicle having a hybrid drive system with a hill descent control.
2. Disclosure Information
Vehicles intended to be driven off-road are sometimes equipped with a hill descent control. Typically, hill descent controls use powertrain braking, as well as friction braking, to provide more controlled operation on a severe downgrade. The use of hill descent control in a vehicle equipped with a hybrid powertrain having both engine-driven and electrodrive capability presents a unique challenge inasmuch as although it is desirable to operate a vehicle's traction motor regeneratively, in other words, to use regenerative braking, such regenerative braking may cause one or more wheels to slip undesirably on a severe downgrade.
Certain known regenerative braking systems increase regenerative braking in direct proportion to the magnitude of the slope being negotiated. This, however, may cause unwanted wheel slip.